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        Module&nbsp;daemonize'
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<h1 class="epydoc">Source Code for <a href="ProvCon.wronolib.daemonize%27-module.html">Module ProvCon.wronolib.daemonize'</a></h1>
<pre class="py-src">
<a name="L1"></a><tt class="py-lineno"> 1</tt>  <tt class="py-line"><tt class="py-comment">#!/usr/bin/env python</tt> </tt>
<a name="L2"></a><tt class="py-lineno"> 2</tt>  <tt class="py-line"><tt class="py-keyword">import</tt> <tt class="py-name">sys</tt><tt class="py-op">,</tt> <tt class="py-name">os</tt> </tt>
<a name="L3"></a><tt class="py-lineno"> 3</tt>  <tt class="py-line"> </tt>
<a name="L4"></a><tt class="py-lineno"> 4</tt>  <tt class="py-line"><tt class="py-string">'''This module is used to fork the current process into a daemon.</tt> </tt>
<a name="L5"></a><tt class="py-lineno"> 5</tt>  <tt class="py-line"><tt class="py-string"></tt> </tt>
<a name="L6"></a><tt class="py-lineno"> 6</tt>  <tt class="py-line"><tt class="py-string">Almost none of this is necessary (or advisable) if your daemon is being started</tt> </tt>
<a name="L7"></a><tt class="py-lineno"> 7</tt>  <tt class="py-line"><tt class="py-string">by inetd. In that case, stdin, stdout and stderr are all set up for you to</tt> </tt>
<a name="L8"></a><tt class="py-lineno"> 8</tt>  <tt class="py-line"><tt class="py-string">refer to the network connection, and the fork()s and session manipulation</tt> </tt>
<a name="L9"></a><tt class="py-lineno"> 9</tt>  <tt class="py-line"><tt class="py-string">should not be done (to avoid confusing inetd). Only the chdir() and umask()</tt> </tt>
<a name="L10"></a><tt class="py-lineno">10</tt>  <tt class="py-line"><tt class="py-string">steps remain useful.</tt> </tt>
<a name="L11"></a><tt class="py-lineno">11</tt>  <tt class="py-line"><tt class="py-string"></tt> </tt>
<a name="L12"></a><tt class="py-lineno">12</tt>  <tt class="py-line"><tt class="py-string">References:</tt> </tt>
<a name="L13"></a><tt class="py-lineno">13</tt>  <tt class="py-line"><tt class="py-string"></tt> </tt>
<a name="L14"></a><tt class="py-lineno">14</tt>  <tt class="py-line"><tt class="py-string">    UNIX Programming FAQ</tt> </tt>
<a name="L15"></a><tt class="py-lineno">15</tt>  <tt class="py-line"><tt class="py-string">        1.7 How do I get my program to act like a daemon?</tt> </tt>
<a name="L16"></a><tt class="py-lineno">16</tt>  <tt class="py-line"><tt class="py-string">        http://www.unixguide.net/unix/programming/1.7.shtml</tt> </tt>
<a name="L17"></a><tt class="py-lineno">17</tt>  <tt class="py-line"><tt class="py-string">        http://www.faqs.org/faqs/unix-faq/programmer/faq/</tt> </tt>
<a name="L18"></a><tt class="py-lineno">18</tt>  <tt class="py-line"><tt class="py-string"></tt> </tt>
<a name="L19"></a><tt class="py-lineno">19</tt>  <tt class="py-line"><tt class="py-string">    Advanced Programming in the Unix Environment</tt> </tt>
<a name="L20"></a><tt class="py-lineno">20</tt>  <tt class="py-line"><tt class="py-string">        W. Richard Stevens, 1992, Addison-Wesley, ISBN 0-201-56317-7.</tt> </tt>
<a name="L21"></a><tt class="py-lineno">21</tt>  <tt class="py-line"><tt class="py-string"></tt> </tt>
<a name="L22"></a><tt class="py-lineno">22</tt>  <tt class="py-line"><tt class="py-string">$Id: daemonize.py 57 2008-12-22 16:05:53Z wroniasty $</tt> </tt>
<a name="L23"></a><tt class="py-lineno">23</tt>  <tt class="py-line"><tt class="py-string">'''</tt> </tt>
<a name="L24"></a><tt class="py-lineno">24</tt>  <tt class="py-line"> </tt>
<a name="daemonize"></a><div id="daemonize-def"><a name="L25"></a><tt class="py-lineno">25</tt> <a class="py-toggle" href="#" id="daemonize-toggle" onclick="return toggle('daemonize');">-</a><tt class="py-line"><tt class="py-keyword">def</tt> <a class="py-def-name" href="ProvCon.wronolib.daemonize'-module.html#daemonize">daemonize</a> <tt class="py-op">(</tt><tt class="py-param">stdin</tt><tt class="py-op">=</tt><tt class="py-string">'/dev/null'</tt><tt class="py-op">,</tt> <tt class="py-param">stdout</tt><tt class="py-op">=</tt><tt class="py-string">'/dev/null'</tt><tt class="py-op">,</tt> <tt class="py-param">stderr</tt><tt class="py-op">=</tt><tt class="py-string">'/dev/null'</tt><tt class="py-op">)</tt><tt class="py-op">:</tt> </tt>
</div><div id="daemonize-collapsed" style="display:none;" pad="++" indent="++++"></div><div id="daemonize-expanded"><a name="L26"></a><tt class="py-lineno">26</tt>  <tt class="py-line"> </tt>
<a name="L27"></a><tt class="py-lineno">27</tt>  <tt class="py-line">    <tt class="py-docstring">'''This forks the current process into a daemon. The stdin, stdout, and</tt> </tt>
<a name="L28"></a><tt class="py-lineno">28</tt>  <tt class="py-line"><tt class="py-docstring">    stderr arguments are file names that will be opened and be used to replace</tt> </tt>
<a name="L29"></a><tt class="py-lineno">29</tt>  <tt class="py-line"><tt class="py-docstring">    the standard file descriptors in sys.stdin, sys.stdout, and sys.stderr.</tt> </tt>
<a name="L30"></a><tt class="py-lineno">30</tt>  <tt class="py-line"><tt class="py-docstring">    These arguments are optional and default to /dev/null. Note that stderr is</tt> </tt>
<a name="L31"></a><tt class="py-lineno">31</tt>  <tt class="py-line"><tt class="py-docstring">    opened unbuffered, so if it shares a file with stdout then interleaved</tt> </tt>
<a name="L32"></a><tt class="py-lineno">32</tt>  <tt class="py-line"><tt class="py-docstring">    output may not appear in the order that you expect. '''</tt> </tt>
<a name="L33"></a><tt class="py-lineno">33</tt>  <tt class="py-line"> </tt>
<a name="L34"></a><tt class="py-lineno">34</tt>  <tt class="py-line">    <tt class="py-comment"># Do first fork.</tt> </tt>
<a name="L35"></a><tt class="py-lineno">35</tt>  <tt class="py-line">    <tt class="py-keyword">try</tt><tt class="py-op">:</tt> </tt>
<a name="L36"></a><tt class="py-lineno">36</tt>  <tt class="py-line">        <tt class="py-name">pid</tt> <tt class="py-op">=</tt> <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">fork</tt><tt class="py-op">(</tt><tt class="py-op">)</tt> </tt>
<a name="L37"></a><tt class="py-lineno">37</tt>  <tt class="py-line">        <tt class="py-keyword">if</tt> <tt class="py-name">pid</tt> <tt class="py-op">&gt;</tt> <tt class="py-number">0</tt><tt class="py-op">:</tt> </tt>
<a name="L38"></a><tt class="py-lineno">38</tt>  <tt class="py-line">            <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">exit</tt><tt class="py-op">(</tt><tt class="py-number">0</tt><tt class="py-op">)</tt>   <tt class="py-comment"># Exit first parent.</tt> </tt>
<a name="L39"></a><tt class="py-lineno">39</tt>  <tt class="py-line">    <tt class="py-keyword">except</tt> <tt class="py-name">OSError</tt><tt class="py-op">,</tt> <tt class="py-name">e</tt><tt class="py-op">:</tt> </tt>
<a name="L40"></a><tt class="py-lineno">40</tt>  <tt class="py-line">        <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">stderr</tt><tt class="py-op">.</tt><tt id="link-0" class="py-name" targets="Method ProvCon.dbui.orm.record.Record.write()=ProvCon.dbui.orm.record.Record-class.html#write"><a title="ProvCon.dbui.orm.record.Record.write" class="py-name" href="#" onclick="return doclink('link-0', 'write', 'link-0');">write</a></tt> <tt class="py-op">(</tt><tt class="py-string">"fork #1 failed: (%d) %s\n"</tt> <tt class="py-op">%</tt> <tt class="py-op">(</tt><tt class="py-name">e</tt><tt class="py-op">.</tt><tt class="py-name">errno</tt><tt class="py-op">,</tt> <tt class="py-name">e</tt><tt class="py-op">.</tt><tt class="py-name">strerror</tt><tt class="py-op">)</tt> <tt class="py-op">)</tt> </tt>
<a name="L41"></a><tt class="py-lineno">41</tt>  <tt class="py-line">        <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">exit</tt><tt class="py-op">(</tt><tt class="py-number">1</tt><tt class="py-op">)</tt> </tt>
<a name="L42"></a><tt class="py-lineno">42</tt>  <tt class="py-line"> </tt>
<a name="L43"></a><tt class="py-lineno">43</tt>  <tt class="py-line">    <tt class="py-comment"># Decouple from parent environment.</tt> </tt>
<a name="L44"></a><tt class="py-lineno">44</tt>  <tt class="py-line">    <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">chdir</tt><tt class="py-op">(</tt><tt class="py-string">"/"</tt><tt class="py-op">)</tt> </tt>
<a name="L45"></a><tt class="py-lineno">45</tt>  <tt class="py-line">    <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">umask</tt><tt class="py-op">(</tt><tt class="py-number">0</tt><tt class="py-op">)</tt> </tt>
<a name="L46"></a><tt class="py-lineno">46</tt>  <tt class="py-line">    <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">setsid</tt><tt class="py-op">(</tt><tt class="py-op">)</tt> </tt>
<a name="L47"></a><tt class="py-lineno">47</tt>  <tt class="py-line"> </tt>
<a name="L48"></a><tt class="py-lineno">48</tt>  <tt class="py-line">    <tt class="py-comment"># Do second fork.</tt> </tt>
<a name="L49"></a><tt class="py-lineno">49</tt>  <tt class="py-line">    <tt class="py-keyword">try</tt><tt class="py-op">:</tt> </tt>
<a name="L50"></a><tt class="py-lineno">50</tt>  <tt class="py-line">        <tt class="py-name">pid</tt> <tt class="py-op">=</tt> <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">fork</tt><tt class="py-op">(</tt><tt class="py-op">)</tt> </tt>
<a name="L51"></a><tt class="py-lineno">51</tt>  <tt class="py-line">        <tt class="py-keyword">if</tt> <tt class="py-name">pid</tt> <tt class="py-op">&gt;</tt> <tt class="py-number">0</tt><tt class="py-op">:</tt> </tt>
<a name="L52"></a><tt class="py-lineno">52</tt>  <tt class="py-line">            <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">exit</tt><tt class="py-op">(</tt><tt class="py-number">0</tt><tt class="py-op">)</tt>   <tt class="py-comment"># Exit second parent.</tt> </tt>
<a name="L53"></a><tt class="py-lineno">53</tt>  <tt class="py-line">    <tt class="py-keyword">except</tt> <tt class="py-name">OSError</tt><tt class="py-op">,</tt> <tt class="py-name">e</tt><tt class="py-op">:</tt> </tt>
<a name="L54"></a><tt class="py-lineno">54</tt>  <tt class="py-line">        <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">stderr</tt><tt class="py-op">.</tt><tt id="link-1" class="py-name"><a title="ProvCon.dbui.orm.record.Record.write" class="py-name" href="#" onclick="return doclink('link-1', 'write', 'link-0');">write</a></tt> <tt class="py-op">(</tt><tt class="py-string">"fork #2 failed: (%d) %s\n"</tt> <tt class="py-op">%</tt> <tt class="py-op">(</tt><tt class="py-name">e</tt><tt class="py-op">.</tt><tt class="py-name">errno</tt><tt class="py-op">,</tt> <tt class="py-name">e</tt><tt class="py-op">.</tt><tt class="py-name">strerror</tt><tt class="py-op">)</tt> <tt class="py-op">)</tt> </tt>
<a name="L55"></a><tt class="py-lineno">55</tt>  <tt class="py-line">        <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">exit</tt><tt class="py-op">(</tt><tt class="py-number">1</tt><tt class="py-op">)</tt> </tt>
<a name="L56"></a><tt class="py-lineno">56</tt>  <tt class="py-line"> </tt>
<a name="L57"></a><tt class="py-lineno">57</tt>  <tt class="py-line">    <tt class="py-comment"># Now I am a daemon!</tt> </tt>
<a name="L58"></a><tt class="py-lineno">58</tt>  <tt class="py-line"> </tt>
<a name="L59"></a><tt class="py-lineno">59</tt>  <tt class="py-line">    <tt class="py-comment"># Redirect standard file descriptors.</tt> </tt>
<a name="L60"></a><tt class="py-lineno">60</tt>  <tt class="py-line">    <tt class="py-name">si</tt> <tt class="py-op">=</tt> <tt class="py-name">open</tt><tt class="py-op">(</tt><tt class="py-name">stdin</tt><tt class="py-op">,</tt> <tt class="py-string">'r'</tt><tt class="py-op">)</tt> </tt>
<a name="L61"></a><tt class="py-lineno">61</tt>  <tt class="py-line">    <tt class="py-name">so</tt> <tt class="py-op">=</tt> <tt class="py-name">open</tt><tt class="py-op">(</tt><tt class="py-name">stdout</tt><tt class="py-op">,</tt> <tt class="py-string">'w'</tt><tt class="py-op">)</tt> </tt>
<a name="L62"></a><tt class="py-lineno">62</tt>  <tt class="py-line">    <tt class="py-name">se</tt> <tt class="py-op">=</tt> <tt class="py-name">open</tt><tt class="py-op">(</tt><tt class="py-name">stderr</tt><tt class="py-op">,</tt> <tt class="py-string">'w'</tt><tt class="py-op">,</tt> <tt class="py-number">0</tt><tt class="py-op">)</tt> </tt>
<a name="L63"></a><tt class="py-lineno">63</tt>  <tt class="py-line">    <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">dup2</tt><tt class="py-op">(</tt><tt class="py-name">si</tt><tt class="py-op">.</tt><tt class="py-name">fileno</tt><tt class="py-op">(</tt><tt class="py-op">)</tt><tt class="py-op">,</tt> <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">stdin</tt><tt class="py-op">.</tt><tt class="py-name">fileno</tt><tt class="py-op">(</tt><tt class="py-op">)</tt><tt class="py-op">)</tt> </tt>
<a name="L64"></a><tt class="py-lineno">64</tt>  <tt class="py-line">    <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">dup2</tt><tt class="py-op">(</tt><tt class="py-name">so</tt><tt class="py-op">.</tt><tt class="py-name">fileno</tt><tt class="py-op">(</tt><tt class="py-op">)</tt><tt class="py-op">,</tt> <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">stdout</tt><tt class="py-op">.</tt><tt class="py-name">fileno</tt><tt class="py-op">(</tt><tt class="py-op">)</tt><tt class="py-op">)</tt> </tt>
<a name="L65"></a><tt class="py-lineno">65</tt>  <tt class="py-line">    <tt class="py-name">os</tt><tt class="py-op">.</tt><tt class="py-name">dup2</tt><tt class="py-op">(</tt><tt class="py-name">se</tt><tt class="py-op">.</tt><tt class="py-name">fileno</tt><tt class="py-op">(</tt><tt class="py-op">)</tt><tt class="py-op">,</tt> <tt class="py-name">sys</tt><tt class="py-op">.</tt><tt class="py-name">stderr</tt><tt class="py-op">.</tt><tt class="py-name">fileno</tt><tt class="py-op">(</tt><tt class="py-op">)</tt><tt class="py-op">)</tt> </tt>
</div><a name="L66"></a><tt class="py-lineno">66</tt>  <tt class="py-line"> </tt><script type="text/javascript">
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